We think a project is recognized by its "guid" (found inside .xdk main file), but we need to share some code with other developers and would like to share the ".xdk" too... presently each developer has his own account and we "clone" settings from one client to the others... maybe we could share the same xdk account (never tried, is it possible/legal?)... can it be solved any other way?
As far as I know, you can share all the XDK local files without problem, using each developer its account. Once I sent the complete folder of an XDK project to other developer and we both were able to open and build it with it, with our own accounts.
If you set the GUID to all zeroes the XDK will automatically assign a unique GUID for each copy of the project. I'm not clear on precisely what the GUID is used for, so I cannot tell you if there is a problem associated with not zeroing it out. However, I've done tests with many customer projects without changing that item in my copy of their project, and I've not heard of any issues. You project is associated with your account, I believe non-unique GUIDs can cause a problem within your account, but should have no bearing if the same GUID shows up in different accounts.